The Broadband High Power THz User Facility at the Jefferson Lab - FEL

Transcription

1 The Broadband High Power THz User Facility at the Jefferson Lab - FEL J. Michael Klopf Jefferson Lab Core Managers Meeting June 8, 2006

2 Jefferson Lab Site

3 Free Electron Laser Facility / THz Lab

4 What is the THz Gap? 1 THz = Hz

5 Why is there a THz Gap? Electronics - radios 0.01 Photonics light bulbs THz K Black Body 1E-4 Watts/cm -1 /mm 2 /sr 1E-6 1E-8 1E-10 Tom Crowe, UVA Frequency (cm -1 )

6 The FCC and the THz Gap THz radiation also lies in the unallocated frequency space due to the lack of sources and detectors

7 Why is THz Radiation Important? THz radiation can enable imaging capabilities complementary to X-ray imaging without the problems typical of ionizing radiation medical imaging security technologies manufacturing pharmaceuticals THz frequencies are resonant with many vibrational and rotational modes in molecules which could not previously be probed Energy range of THz spectrum O(meV) overlaps with band gaps of superconductors excitation energy for protein folding phonon energies Defense related applications in explosives/mine detection as well as short range communications THz pulses can be used for novel nonlinear optical experiments THz source at the FEL has proven to be a useful accelerator diagnostic

8 How Light is Produced Light (electromagnetic waves) is made by accelerating an electron. e - light

9 Radiated Power From an Electron The power radiated by an accelerating electron is given by Larmor s Formula: Power = where γ = 2 2 2e a 4 3 m m o 3c γ ( cgs units)

10 Radiated Power From an Electron Bunch When extremely short bunches of N electrons are accelerated, the power scales as: Power = 2( Ne) 3c 3 2 a 2 γ 4 In most cases, such as in solid state electronics, γ = 1 At the JLab FEL, γ ~ 200, which results in an increase in power of over 9 orders of magnitude!!!

11 JLab FEL and THz Source

12 JLab FEL and THz Source Photons/sec/0.1%BW/mm 2 /milliradian 2 1x x Electron Beam Energy = 3 GeV Bending Radius = 5m MHz (100 ma) E-4 1E LARMOR LIMIT 3GLS 10 x 500 microns (x500 for ID) JLAB THz JLAB FEL FSU 4GLS Photon Energy (ev) UVFEL 4GLS 4GLS 1x1nm (x10 10 for multiparticle) 2GLS 500x1000 microns LCLS XFEL Gwyn Williams - file brt_1.bas May 25, 2006

13 Coherent THz Radiation From Short Electron Bunches acceleration of e- bunches off crest produces a monotonic energy spread or chirp HR chicane provides dispersion and path geometry to compress the chirped pulses long chirped pulse compressed pulse G. Larry Carr, BNL

14 JLab THz Beamline Optics Vertical Position M4 F3 Vertical Position THz To User Facility Funding US Army NVL x10-1 m -100mm x200mm Horizontal Position F2 Vertical Position x10-2 m -30mm 60x60mm Horizontal Position Vertical Position M2-3x10-2 m 60x60mm -30mm Horizontal Position -1.0x10-1 m -100mm Horizontal Position 200x200mm M x200mm Vertical Position x1 0-2 m Optical calculations by Oleg Chubar, Paul Dumas -40mm Horizontal Position

15 JLab THz Beamline

16 JLab FEL THz User Lab

17 State of the JLab THz Source and User Facility The beamline has been commissioned and is operational. THz spectrum has been measured and is routinely used to for accelerator diagnostics. A new vacuum spectrometer has been tested and is being commissioned for vacuum operation. Beam power measurements are underway. As the first ever high power source, characterization methods must be developed and tested. The first imaging tests have been performed and beam profiling measurements are underway. Collaborative experiments on electro-optic switching have been conducted with a researcher from Cornell. Measurements to determine safety equipment have been conducted. Experiments to determine the effects of exposure to high power THz sources have been proposed for the JLab THz lab.

18 Beam Image of JLab FEL THz Source Measured Calculated

19 Measured JLab FEL THz Spectrum Wavenumber (cm -1 ) JLab - FEL THz spectrum τ p ~ 350 fs Intensity (arb. units) THz 0.00

20 Applications of JLab FEL High Power THz Facility Basal cell carcinoma (skin cancer) shows malignancy in red. (courtesy of Teraview Ltd.) 1 mw source images 1 cm 2 in 1 minute 100 W source images whole body (50 x 200cm) in few seconds

21 Applications of JLab FEL High Power THz Facility A tooth cavity shows up clearly in red. (courtesy of Teraview Ltd.)

22 Applications of JLab FEL High Power THz Facility proof of principal experiments for remote sensing with high resolution active imaging portable source development Calculations using antenna coupled bolometer sensitivities Indicate that about 100 W is required for this application

23 Summary A new generation broadband high power THz source has been commissioned at the Jefferson Lab FEL, which offers novel capabilities and unprecedented opportunities for research, security, military, medical and other commercial applications. The Jefferson Lab FEL THz source continues to be characterized and is already used routinely for accelerator diagnostics. Preliminary tests for developing the real-time imaging capabilities are underway. Measurements to determine the safety issues related to the high power source have been made and are continuing. A compact high power THz source is being developed at Advanced Energy Systems in collaboration with the Jefferson Lab FEL. Started user program at Jefferson Lab FEL, proposals invited.

24 Acknowledgements Larry Carr Oleg Chubar Paul Dumas Alan Todd Vincent Christina Tom Crowe Fred Dylla George Neil Michelle Shinn Joe Gubeli Matt Thomas NSLS, Brookhaven, USA Soleil Project, France Soleil Project, France Advanced Energy Systems, USA Advanced Energy Systems, USA University of Virginia, USA Jefferson Lab, USA Jefferson Lab, USA Jefferson Lab, USA Jefferson Lab, USA SURA, USA Plus the JLab FEL team. Supported by: U.S. Department of Energy - Contract DE-AC05-84ER40150 U.S. Department of Defense - ONR, AFOSR and ARO-NVL Jefferson Science Associates - JSA

25 Some of the FEL Team